Although the available power of ocean wind wave has been calculated at 2.5.times.10.sup.12 W globally, present wave energy recovering technology is only marginally economical even along a high energy coastline such as the United Kingdom. This is in large part due to limited available energy density, which requires large numbers of energy collectors to be strung out along a given length of coastline in order to recover economically feasible quantities of wave energy.
A number of attempts have been made to focus tidal and wave energy into a limited area to allow for efficient conversion for power production, including those disclosed in the patents of Arpin (U.S. Pat. No. 2,069,715), Danel (U.S. Pat. No. 2,435,576), Gay (U.S. Pat. No. 2,441,759), Southwick (U.S. Pat. No. 2,820,148), Conn, et al. (U.S. Pat. No. 4,034,231), Borgren (U.S. Pat. No. 4,363,564) and Mehlum (Re 32054). The Danel, Gay, Southwick and Borgren patents each describe the use of sea walls of various geometries which are designed to channel wave energy to one or more focal points. The Mehlum patent discloses a variation on the solid converging sea walls or channels which involves the creation of a diffraction grating formed from discrete structures arranged in a grid pattern. The grid pattern becomes a Fresnel lens, focusing the energy by diffracting the incoming waves. Finally, the Conn, et al. patent relies only partially on redirection of wave energy. Instead, this device is a V-shaped pier-like structure with a number of water turbines distributed at different points of the structure. Rather than bringing the waves to the turbine, or the conversion device, the turbines are distributed to utilize a section of the wave front.
A common concern of each of these devices is the sea wall or channel. The construction of permanent structures can be expensive and potentially environmentally destructive by altering the local ocean current patterns. Also, changes in sea topography due to storms and erosion can cause the ideal location for energy collector placement to shift, rendering an expensive permanent structure less effective.
The need for a portable reef or sea wall has been addressed in U.S. Pat. Nos. 2,069,715 of Arpin and 3,886,751 of Porraz Jimenez Labora.
The artificial reef of Arpin is limited in that its structure is relatively shallow, either in a triangular or semicircular cross section. While some modifications of wave patterns in shallow water is possible, the entire purpose of this artificial reef is to provide a nucleation point to accumulate sand to form a sandbar. This type of structure would not be effective in providing sufficient wave channeling for energy conversion purposes.
The aquatic construction modules of Poraz Jimenez Labora come closer to meeting the needs of a portable, sturdy structure for modifying water flow patterns. However, the interlocking edges of the modules must be individually aligned and linked together during assembly of the reef or other protective barrier. This procedure, while suitable for construction of temporary levees and channels well in advance of flooding, where rapid assembly of the barrier is not critical, is extremely impractical for construction in existing bodies of water, especially in the presence of ocean swells, using conventional floating cranes and riggings.